A Rare Case of Idiopathic Granulomatous Hypophysitis: When Imaging Misleads and Histology Reveals

Abstract Idiopathic granulomatous hypophysitis (IGH) is an exceedingly rare inflammatory disorder of the pituitary gland that often mimics pituitary adenomas clinically and radiologically, leading to diagnostic challenges. This report presents the case of a 31-year-old male initially suspected of having a nonfunctioning pituitary adenoma due to progressive visual diminution and headache. Despite imaging suggesting an adenoma, histopathological examination following endoscopic endonasal transsphenoidal excision revealed diffuse granulomatous inflammation with epithelioid cells and Langhans’ giant cells, confirming IGH after exclusion of other systemic granulomatous conditions. This case highlights the critical role of histopathology in differentiating IGH from more common pituitary pathologies, particularly when imaging findings are inconclusive or misleading. Early and accurate diagnosis is crucial for appropriate management, which typically involves corticosteroids.